1. Field of the Invention
The present invention relates to a picture data recording method of recording picture data. The present invention also relates to a picture data storage medium which stores picture data. The present invention also relates to a picture data playback apparatus and method of playing back picture data.
2. Description of the Related Art
In recent years, a DVD (Digital Versatile Disk) has been developed as a high-density recording medium. A DVD video scheme is defined as a scheme of recording, on this medium, sub-picture data such as audio and subtitle data as well as main picture data.
Currently, a scheme of recording high-resolution main picture data and sub-picture data on a recording medium such as an optical disk has been examined as extension of the current DVD video standard.
The high-resolution main picture data and sub-picture data are synthesized and output to a high-resolution monitor that can cope with a high resolution. However, since standard monitors (NTSC monitors) are popular currently, the synthesized data of high-resolution main picture data and sub-picture data is converted to a standard resolution, i.e., down-converted and then output to the standard monitor.
Since sub-picture data contains steep edges, the image quality readily degrades upon down-conversion. That is, the above-described method of outputting high-resolution data to a standard monitor may degrade the image quality of sub-picture data displayed on the standard monitor.